Conventionally, pneumatic rubber vehicle tires are produced by molding and curing a green (uncured) partially shaped tire in a molding press. The green tire is pressed outwardly against a mold surface by means of an inner fluid-expandable bladder. By this method, the green tire is shaped against the outer mold surface that defines the tire tread pattern and configuration of the sidewalls. By application of heat and pressure, the tire is molded and cured at elevated temperatures.
In general practice, the expansion of the bladder is accomplished by application of internal pressure to the inner bladder cavity which is provided by a fluid such as a gas, hot water and/or steam which also may participate in the transfer of heat for the curing or vulcanization of the tire. The tire after molding and curing is allowed to cool somewhat in the mold, sometimes aided by adding cold or cooler water supplied to the bladder. Then the mold is opened, the bladder is collapsed, including release of its internal fluid pressure, and the tire is removed from the tire mold. Such use of tire curing bladders is well known to those having skill in the art.
A cross sectional view of conventional tire curing bladder 100 is illustrated in FIG. 6; the bladder 100 has a toroidal shape, open at the inner side. The bladder has opposing bead regions 102 and an expansion area 104 between the bead regions 102. The bead regions are provided with means to secure the curing bladder to the press mechanism, enabling the bladder to expand outwards and into a green tire. During expansion of the bladder 100 into a tire cavity 106 during molding, the shoulder portions of the bladder 100 do not consistently make contact with the tire interior, leaving a gap 108 and trapped air between the tire bladder and the tire cavity, see FIG. 7. While the tire is fully cured, the gap may a cured defect in the tires.